The project aims at advancing the understanding of the extrinsic regulations, humoral and cellular, that apply to neural tissue during development and adult life. Specifically, the intent is to continue investigating in vitro neural cell systems, such as sympathetic and sensory ganglionic and spinal cord cells, with regard to the roles that glial cells and Nerve Growth Factor may play in the support and/or regulation of neuronal behaviors. In particular, attention will be directed to Nerve Growth Factor-related properties of neuronal and glial membranes. BIBLIOGRAPHIC REFERENCES: S.Varon. 1975. In vitro approaches to the study of neural tissue aging. In Survey of the Aging Nervous System, G. Maletta (ed.), DHEW Pub. #(NIH) 74-296, pp. 59-76.